The present invention relates generally to rotary machines, and more particularly to an energy management system for rotary machines.
Rotary machines include, without limitation, turbines for steam turbines, compressors and turbines for gas turbines and turbines for hybrid fuel cells. A steam turbine has a steam path that typically includes, in serial-flow relationship, a steam inlet, a steam generating device, a turbine and a steam outlet. A gas turbine has a gas path that typically includes, in serial-flow relationship, an air intake (also known as an inlet), a compressor, a combustor, a turbine, and a gas outlet. A hybrid fuel cell has a gas path that typically includes, in serial-flow relationship, an air intake, a compressor, a fuel cell, a turbine and a gas outlet. In the abovementioned turbines, the gases (steam or gas) flow to a turbine that extracts energy for driving a turbine shaft to produce output power for powering an electrical generator. A turbine is typically operated for extended periods of time at a relatively high base load for powering the electrical generator to produce electrical power in a utility grid, for example. In some cases, the rotary machine is subject to a grid transient or load interruption that causes the output breakers of the electrical generator to open thereby resulting in a sudden loss of load that can cause an overspeed condition. The loss of load, in addition to a response time of the rotary machine to the load interruption, may cause an acceleration effect to the rotary components and, at times, result in mechanical damage therein. Furthermore, the loss of load in the rotary machine may also damage the electrical components by providing thermal stresses therein. In cases involving turbines comprising recuperators, for example, the recuperator functions to recover heat from a turbine exhaust and stores excess that, at times, maintains the rotation and increases the acceleration of the rotary equipment in the machine when the load interruption occurs.
By way of example and not limitation, typical grid transients and load interruptions include voltage sags, voltage surges, voltage interruptions, single phase failures, phase to phase faults and phase to ground faults. Some conventional turbine designs comprise resistors disposed to receive a build-up of electrical energy in the event of such casualties. While these types of conventional designs have proved to be quite reliable, the resistors, however, are sized for worst case operating conditions (e.g. such as high ambient temperatures and no cooling sources available) and are typically overdesigned for normal operating conditions. In addition, such robust designs increase the total cost in manufacturing the rotary machine.
Accordingly, there is a need in the art for a rotary machine having improved energy management control characteristics.
On embodiment of the present invention comprises an energy management system for a power generating device having a working fluid intake in which the energy management system comprises an electrical dissipation device coupled to the power generating device and a dissipation device cooling system configured to direct a portion of a working fluid to the electrical dissipation device so as to provide thermal control to the electrical dissipation device.